1. Field of the Invention
The invention relates to broadband systems, and in particular, to broadband systems that utilize narrowband circuit switches for various call capabilities.
2. Background of the Prior Art
Conventional circuit switches provide the backbone for many current telecommunications networks. These switches process call signaling and extend the call connection towards the destination. They have also been developed to include sophisticated capabilities. Examples include caller validation, number screening, routing, connection control, and billing. These switches are also used to deploy various services. Examples include calling cards, "800" calling, voice messaging, and class services.
At present, Asynchronous Transfer Mode (ATM technology is being developed to provide broadband switching capability for telecommunications calls, which are requests for telecommunications services. Some ATM systems have used ATM cross-connects to provide virtual connections, but cross-connect devices do not have the capacity to process signaling used by telecommunications networks to set-up and tear down calls. Thus, ATM cross-connects cannot make connections on a call-by-call basis. As a result, connections through cross-connect systems must be pre-provisioned which creates a relatively rigid switching fabric. Due to this limitation, ATM cross-connect systems have been used primarily to provide dedicated connections, such as permanent virtual circuits (PVCs) and permanent virtual paths (PVPs). But, they do not provide ATM switching on a call by call basis as required to provide switched virtual circuits (SVCs) or switched virtual paths (SVPs). Those skilled in the art are well aware of the efficiencies created by using SVPs and SVCs as opposed to PVCs and PVPs because SVCs and SVPs utilize bandwidth more efficiently.
ATM switches have also been used to provide PVCs and PVPs. Because PVCs and PVPs are not established on a call-by-call basis, the ATM switch does not need to use its call processing or signaling capacity. ATM switches require both signaling capability and call processing capability to provide SVCs and SVPs. In order to achieve virtual connection switching on a call by call basis, ATM switches are being developed that can process calls in response to signaling to provide virtual connections for each call. These systems cause problems, however, because they must be very sophisticated to support current networks. These ATM switches must process high volumes of calls and transition legacy services from existing networks. An example would be an ATM switch that can handle large numbers of POTS, 800, and VPN calls.
Currently, ATM multiplexers are capable of interworking traffic of other formats into the ATM format. These are known as ATM interworking multiplexers (muxes). ATM multiplexers are being developed that can interwork traffic into ATM cells and multiplex the cells for transport over an ATM network. These ATM mux are not used to implement virtual connections selected on a call-by-call basis.
Unfortunately, there is a need for efficient systems that can integrate the capabilities of broadband components with the capabilities of conventional circuit switches. Such a system would provide ATM virtual connections on a call-by-call basis, but support the numerous services currently provided by circuit switches.